The apparatus and method of the present invention relates to positioning a drilling tool normal to a work surface and, more particularly, to ensuring that the position of the drilling tool remains normal to the work surface during operation of the drilling tool.
In many applications, it is imperative that holes in a structure, such as an aircraft, watercraft, building, bridge, or various other types of objects, are drilled perpendicular to the work surface. When holes are not drilled perpendicular to the work surface, the fasteners applied to the holes may not securely fasten the structure, which may negatively affect the integrity of the structure. In addition, the heads of fasteners applied to non-perpendicular holes may not lie flat on the surface of the structure, creating a problem in applications requiring a smooth surface, such as on the outer surface of an aircraft, watercraft, building, and the like.
In the aircraft industry, for example, fastener holes must be drilled within two degrees of normal in order to ensure the structural integrity of an aircraft. Holes that are not drilled perpendicular to the work surface may cause the fastener to not securely fasten parts of the aircraft or may adversely affect the performance of the aircraft. Thus, the non-perpendicular fastener hole must be repaired immediately, which interrupts the manufacturing process with unscheduled or out-of-sequence work to repair the defect. Because a considerable amount of labor is required to repair the non-perpendicular hole and because the repairs are not scheduled, the aircraft manufacturing process is typically interrupted for a significant amount of time, which is costly, not only with respect to the cost of labor, but also regarding the delay in delivery of the aircraft.
The conventional way to at least decrease the number of non-perpendicular holes that are drilled in a structure is to utilize a mechanical drill guide. A mechanical drill guide is typically a metal or plastic piece that must be held on the surface of the area to be drilled. The drill guide has at least one hole through which the drill bit may extend. The hole defined by the drill guide is perpendicular to the surface on which the drill guide is placed. The holes may be various sizes to guide various sizes of drill bits. After selecting the appropriate size hole in the drill guide, that hole must be placed over the area of the work surface to be drilled, and the drill bit is placed within the hole to align the drill bit with the area to be drilled. The wall of the drill guide hole about the drill bit keeps the drill operator from yawing the drill from side to side or pitching the drill bit up and down while the drill bit is within the hole. Therefore, the drill guide helps the drill operator to drill consistently perpendicular holes in a structure.
The user of a drill guide, however, must hold the drill guide onto the work surface with one hand and operate the drill with the other hand. In easily accessible locations, operating a drill with one hand is not a problem. In areas with limited access, however, it may not be physically possible for a drill operator to get in a position to be able to control the drill with only one hand. For instance, in the aircraft industry, drill operators typically must use two hands to drill holes around the stringers and frames in the fuselage of the aircraft, in the wing-stub join area of a Boeing 737 aircraft, and in the lower lobe region of a wide body aircraft because the drill operators do not have sufficient visual or spatial access in order to use one hand in these applications. Furthermore, drill operators generally must use both hands to operate certain types of drills, such as a ninety degree drill motor. Thus, when both hands must be used to operate the drill, the drill operator cannot also hold a drill guide on the work surface, which presents a substantial risk that these holes will not be drilled perpendicular to the work surface and, therefore, require costly repairs. Drill guides may, instead, be held upon a work surface by a clamp or the like. In many locations, however, it is difficult, if not impossible, to clamp the drill guide to the work surface.
Drill guides are also not useful in all situations because there may not be sufficient space to place a drill guide on certain work surfaces, such as in areas with severely limited access or on very small areas. In addition, even if the drill operator is able to initially position the drill guide properly on the work surface to be drilled, it may be difficult or impossible for the drill operator to continue to view the work surface and drill guide during drilling. As such, the drill operator cannot ensure that the drill will remain normal to the work surface throughout the drilling process.
Therefore, there exists a need in the industry for a drill operator to ensure that perpendicular holes are drilled in work surfaces regardless of the location or size of the work surfaces, such that fewer costly repairs of non-perpendicular holes will be required. In particular, there is a need to maintain normality of the drill to the work surface throughout the drilling process without having to use one hand to hold a drill guide on the work surface. Additionally, there is a need to provide a drill operator with a view of whether the drill is normal to the work surface in areas where the operator generally cannot view the area being drilled, i.e., when drilling blind holes.